End cap relief valve mechanism for a filter

ABSTRACT

An oil filter includes a housing  14  having an end plate  20  attached to the open end thereof. The end plate  20  includes an outlet opening and inlet openings  22.  An anti-drainback valve  49  is provided adjacent the end plate. A filter element having an end cap at each end is positioned within the housing. The end cap  50  remote from the end plate includes a plurality of openings  52  spaced from a closed central portion  51.  A spring valve  60  cooperates with the end cap  50  and the interior wall of the housing to alternately allow and disallow oil flow through the end cap openings depending upon the differential pressure across the end cap  50.  The spring valve  60  and the end cap  50  can be operationally interengage to provide a relatively flat profile. Depressions  72  (FIG.  5 ) may be included between the arms  62  of the spring valve to provide a flow path should the spring valve be flattened against the housing during operation of the filter.

BACKGROUND OF THE INVENTION

The present invention pertains to fluid filters and, more particularly,an end cap relief valve mechanism for a fluid filter.

Ordinarily, fluid filters, such as oil filters, are provided with reliefvalves in order to bypass the filter element in the event that the oilfilter becomes clogged during use. The oil filter usually comprises ahousing or shell having an open end closed by an end plate. The endplate usually contains one or more inlet openings and an outlet opening.Within the housing is an annular filter media pack. Normally, there is avalve comprised of a valve seat, a valve member and a spring for biasingthe valve to the closed position disposed within the housing. The valveis commonly secured to the filter media pack.

Takahara Patent No. 5,759,351 shows an oil filter having a plate springfor biasing a filter pack within a housing. When the filter pack becomesclogged, the pressure in the housing increases and the relief valveopens to keep the flow rate of the oil supplied to the engine. Thefilter pack does not include end caps and the relief valve of Takaharais structurally different from that of the applicant.

Sundholm Patent No. 5,019,251 discloses a filter having a relief valvemechanism with a spiral spring that is relatively bulky.

Cantoni Patent No. 4,885,082 reveals an oil filter with amulti-component pressure relief valve having a bulky return spring. Theprior art relief valves, as exemplified by those shown in the citedreferences, are constructed separate from the end cap, and properpositioning of the valve within the housing of the fluid filter wassometimes difficult and/or time consuming. The prior relief valves wererelatively bulky and occupied considerable volume within the housing ofthe oil filter. Consideration was given to reducing the number of partsof the valve in order to reduce the cost and to enhance positioning ofthe valve and facilitate assembly of the fluid filter.

An object of the present invention is to provide an improved fluidfilter having a relief valve mechanism formed in part by an end cap,which overcomes difficulties and disadvantages of prior fluid filters.

Another object of the present invention is to provide an improved fluidfilter that incorporates a relief valve mechanism as a part of an endcap to provide a relief valve mechanism that is compact, has a lowprofile and is less costly than prior relief valve mechanisms, thusallowing the fluid filter to be shorter, yet have the same filtrationand flow characteristics as prior taller fluid filters.

Other objects and advantages of the present invention will be made moreapparent in the description which follows.

SUMMARY OF THE INVENTION

A fluid filter, for example, an oil filter comprises a housing that isopen at one end and closed at the other end by an end plate. The endplate has at least one inlet opening and one outlet opening therein.Filter media is disposed in the housing. An end cap is provided at eachend of the filter media. An anti-drain back valve, disposed between theend plate and an end cap of the filter media adjacent the end plate,cooperates with the inlet opening to prevent the back flow of oil therethrough in use. The end cap remote from the end plate has at least oneopening in the central portion thereof. A spring cooperates with the endcap remote from the end plate to close the opening in the end cap and isresponsive to the pressure within the housing to open the flow path whenthe oil pressure in the housing exceeds a predetermined value. The endcap remote from the end plate and the spring comprise a relief valvemechanism. The spring also functions to load the filter media and toretain the anti-drain back valve in position between the end capadjacent the end plate and the end plate. The spring is provided withspaced projections which maintain a flow path should the spring beflattened against the interior of the housing and thereby permit flow ofoil around the spring to permit desired operation of the relief valvemechanism. The spring and the end cap remote from the end plate areconstructed and arranged to provide an end cap relief valve mechanismthat has a flat profile and occupies little more space than the end capalone.

BRIEF DESCRIPTION OF THE INVENTION

There is shown in the attached drawing a presently preferred embodimentof the invention, wherein like numerals in the various views refer tolike elements and wherein,

FIG. 1 is a schematic perspective view, partially broken away, of afluid filter embodying the end cap relief valve mechanism of the presentinvention, with the end cap valve mechanism being shown in the closedposition;

FIG. 2 is a schematic perspective view, partially broken away, similarto FIG. 1, of a fluid filter embodying the end cap relief valvemechanism of the present invention, with the end cap relief valvemechanism being shown in the open position;

FIG. 3 is a plan view of the end cap of the end cap relief valvemechanism;

FIG. 4 is a cross-section of the end cap taken along the line 4—4 ofFIG. 3;

FIG. 5 is a plan view of the spring of the end cap relief valvemechanism;

FIG. 6 is a cross-section of the spring taken along the line 6—6 of FIG.5;

FIG. 7 is a detail cross-section taken generally along the line 7—7 ofFIG. 5;

FIG. 8 is a cross-section showing the relationship of the end cap andthe spring of the end cap relief valve mechanism, with the end caprelief mechanism shown in the closed position; and

FIG. 9 is a cross-section showing the relationship of the end cap andthe spring of the end cap relief valve mechanism, with the end caprelief valve mechanism in the open position.

DETAILED DESCRIPTION OF THE INVENTION

There is shown in FIGS. 1 and 2 a schematic representation of a fluidfilter 10 embodying the relief valve mechanism 12 of the presentinvention. The fluid filter 10, which can be an oil filter, includes ahousing or shell 14 having a closed end 16 and an open end 18. The openend 18 of the housing 14 is closed by an end plate 20 that is providedwith one or more inlet openings 22 disposed radially outwardly from thecenter axis of the fluid filter 10 and an outlet opening 24 disposedgenerally centrally of the end plate 20. The portion of the end plate 20forming the outlet opening 24 is internally threaded so as to receive anexternally threaded engagement member (not shown). Other connections maybe used, as would be known to persons skilled in the art. The end plate20 is suitably positioned and secured in the open end 20 of the housing14. A cover or end ring 21 is secured to the housing 14 outwardly fromthe end plate 18 in a conventional manner, for example, by adouble-rolled seam. The cover 21 has a circular recess 23 formed thereinfor receiving a sealing gasket 26.

Disposed within the housing 14 is a filter media pack 30 which comprisesa central perforated core 32 having a suitable filter media 34 carriedthereon. The core 32 is typically fabricated from relatively thin sheetmetal, such as steel or aluminum, that is stamped to provide theopenings in the core and is then coiled to form a cylinder of thedesired diameter. The filter media 34 may comprise a conventionalpleated paper or a wound filter media. Each end of the filter media 34may be potted in a suitable adhesive or plastisol to help maintain theshape of the filter media during handling and in use. See, for example,the adhesive 29 at the lower end of the filter media 34. For purposes ofbetter showing the top of the pleated filter media, no adhesive is shownat the upper end of the filter media 34 in FIGS. 1 and 2.

An end cap 40 closes the lower end of the filter media pack 30. The endcap 40 may be secured to the filter media 34 or it can be separatetherefrom. The end cap 40 comprises a support member 46, which engagesthe lower end of the filter media 34 and a generally cylindrical portion48 having a circular flange 47 at the lower end that engages the portionof the end plate 20 that forms the outlet opening 24. The flange 47cooperates with the end plate 20 to help retain a resilient valve member49 in place. The valve member 49, which may be made from a natural or anartificial rubber, functions to permit the entry of fluid through theinlet openings 22 into the housing 14, but to prevent the reverse flowof oil through the openings 22. The valve member 49 is sometimesreferred to as an anti-drain back valve.

The relief valve mechanism 12 of the present invention includes agenerally circular end cap 50, which is remote from the end plate 20,and extends over the top of the filter media pack 30 and engages theupper end thereof. The end cap 50 may be secured to the filter media 34or it can be separate therefrom. The end cap 50 is imperforate exceptfor one or more openings 52 spaced radially outwardly from the centerthereof. The openings 52 are arranged in a circular pattern that isspaced radially outwardly from the center axis of the end cap 50. Theend cap 50 includes a cylindrical peripheral rim 54 that has anoutwardly flared flange 56 at the lower end thereof. Cooperating withthe end cap 50 is a valve spring or plate spring 60 that performsmultiple functions. First, the spring 60 abuts the interior of thehousing 14 and loads or pushes the filter media pack 30 downwardlytoward the end plate 20 so as to urge the lower end cap 40 downwardlyagainst the anti-drain back valve 49 to retain the anti-drain back valve49 in place. Second, the spring 60 cooperates with the end cap 50 tonormally close the flow path through the openings 52 and in response toa predetermined pressure within the housing 14 to open the flow paththrough the openings 52, as will be more fully explained hereinafter.

Turning to FIGS. 3 and 4 there is better seen the end cap 50 of thepresent invention. The end cap 50 has a relatively flat profile. Thecentral portion 51, which is imperforate except for the openings 52, isdepressed from the top outer surface of the end cap 50. The openings 52are shown as being circular, however, it will be understood by personskilled in the art that other configurations are possible within thescope of the invention. The openings 52 could be square, oval, orcrescent shaped. Furthermore, the size of the openings 52 could bevaried depending upon the specific design parameters for flow necessarywith a particular fluid filter. The top surface of the end cap 50 isprovided with a ridge or elevated circular portion 53 that will helpstiffen or rigidify the end cap 50 in use.

With reference to FIGS. 5-7, there is better shown the spring 60 thatcontrols the flow of fluid through the openings 52 in the end cap 50 andhelps to retain the anti-drain back valve 29 in position between thelower end cap 40 and the end plate 20. The spring 60, as shown, iscomprised essentially of a plate made, for example, from steel, formedto shape. The spring 60 includes four outwardly extending arm portions62 that extend upwardly from the central portion 68. The ends 64 of thearm portions 62 are bent downwardly. The central portion 68 of thespring 60 is relatively flat and has an opening 70 in the centerthereof, which is in alignment with the imperforate central portion 51of the end cap 50. Provided in the spring 60 are depressions 72 whichare intended to assure that a spacing remains between the interior ofthe housing 14 and the spring 60 and to provide a flow path should thespring 60 be flattened against the interior of the housing. Thisconstruction assures that there will be flow of oil over the top of thevalve spring 60 so as to enable proper operation of the relief valvemechanism.

With reference to FIGS. 8 and 9, there is better shown the cooperationof the spring 60 and end cap 50 of the end cap relief valve mechanism12. The spring 60 and the end cap 50 operationally interengage andprovide a relatively flat profile. The overall height of the twocomponents when assembled within a housing or shell 14 is little morethan the height of the end cap 50. Seal means are provided between theend cap 50 and the spring 60 to prevent fluid from passing directly tothe openings 52 and bypassing the opening 70 in the spring 60. In theembodiment shown, the flattened annular portion 71 radially outward ofthe annular portion 69 extending from the central portion 68 of thespring 60 engages the flattened radial portion 73 radially outward ofthe annular portion 55 extending from the central portion 51 of the endcap 50 to provide a seal for preventing fluid from passing between theend cap 50 and the spring 60 and bypassing the opening 70 in the spring60. In the closed position shown in FIG. 8, the central portion 51 ofthe end cap 50 is positioned upwardly so as to close the opening 70 inthe spring 60 and thus block the flow of fluid (oil) through the end caprelief valve mechanism 12. This is the normal position of the centralportion 51. When the pressure within the housing 14 increases and thefluid pressure differential on the central portion 51 of the end cap 50exceeds a predetermined value, the central portion 51 of the end cap 50below the opening 70 in the spring 60 will flex downwardly, as shown inFIG. 9, to open a flow path through the end cap relief valve mechanism12.

The operation of the fluid filter 10 will now be described. Withreference to FIG. 1, the fluid filter 10 is connected to an engine inthe normal manner. With the engine operating, oil to be cleaned willenter the housing 14 of the fluid filter 10 through the opening oropenings 22 in the end plate 20. Oil will pass through the filter mediapack 30 to be cleaned and through the openings in the core 32 of thefilter media pack 30 for return through the outlet opening 24 to theengine for reuse. If in use, the filter media pack 30 becomes cloggedwith dirt and impurities removed from the oil, the pressure within thehousing 14 will increase. As shown in FIG. 2 and in FIG. 9, when thepressure differential across the end cap exceeds a predetermined value,the central portion 51 of the end cap 50 will flex and separate from thespring 60 and permit oil to flow through the opening 70 in the spring 60and the openings 52 in the end cap 50 and be returned to the engine. Thebypass or return of oil to the engine in the event of a clogged orsubstantially clogged filter media pack 30 will prevent damage to theengine.

The end cap relief valve mechanism of the present invention comprisesbasically two elements-an end cap and a spring that cooperatestherewith. Since there are only two parts, parts costs and manufacturingcosts are reduced. Parts costs are also reduced by making use of the endcap that is normally used with one end of a filter media pack. It willbe understood that the end caps can be integral with filter media orthey can be separate from the filter media. Further, it will beunderstood that the end cap may comprise only the central portion 51that cooperates with a spring 60 to perform the flow control function.In the preferred embodiment, the profile of the end cap relief valvemechanism 12 is relatively flat and occupies little space beyond that ofthe end cap. This allows the fluid filter of the present invention to beshorter than prior devices, yet have the same filtration and flowcharacteristics as such prior taller fluid filters. The spring 60 notonly provides a portion of the relief valve but also a loading functionto bias the filter media pack 34 and the end cap 40 toward the end plate20 to retain the anti-drain back valve 29 in place between the end cap40 and the end plate 20. It is possible to use a different spring, forexample, a coil spring, however, some attributes of the preferredembodiment may be sacrificed.

While we have shown a presently preferred embodiment to the presentinvention, it will be apparent to persons of ordinary skill in the artthat the invention may be otherwise embodied within the scope of theappended claims.

We claim:
 1. In a fluid filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an annular filter media disposed in said housing, said filter media having a first end cap adjacent said end plate and a second end cap remote from said end plate, and a valve member for controlling flow of fluid through the inlet opening, the improvement comprising the second end cap having a plurality of openings surrounding a closed central portion thereof and radially outwardly spaced from the central axis of the second end cap and a spring valve cooperating with said second end cap and said housing for controlling the flow of fluid through said openings, said spring valve closing said openings in the central portion of the second end cap to fluid flow, the second end cap being responsive to the pressure within the housing for opening the said openings in the central portion of the second end cap for fluid flow therethrough when the fluid differential pressure across the second end cap exceeds a predetermined value.
 2. A fluid filter as in claim 1, wherein the valve member comprises an anti-drain valve disposed between the first end cap and the end plate, said spring valve being constructed and arranged to engage the interior of the housing so as to load the filter media and the first end cap to help retain the anti-drain back valve in place.
 3. A fluid filter as in claim 2, wherein the spring valve includes outwardly extending arms extending upwardly from the central portion of the spring.
 4. A fluid filter as in claim 3, including depressions on the spring valve between the arms for providing a flow path should the spring valve be flattened against the interior of the housing in use.
 5. A fluid filter as in claim 1, wherein the central portion of the end cap remote from the end plate is capable of being flexed from a first position against the spring valve to a second position away from the spring valve.
 6. A fluid filter as in claim 5, wherein the spring valve has a central opening therein, the central portion of the second end cap closing the central opening when in the first position and opening the central opening when flexed to the second position, whereby, the spring valve is normally in the first position closing flow of fluid and when the pressure within the housing increases and the differential pressure across the second end cap exceeds a predetermined value, the central portion of the second end cap is flexed to the second position to permit flow of fluid.
 7. An oil filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an anti-drain back valve for precluding return flow of oil through the inlet opening, an annular filter media disposed in said housing, said filter media having a first end cap adjacent said end plate and a second end cap remote from the end plate, the second end cap having a plurality of openings surrounding a closed central portion thereof and radially outwardly spaced from the central axis of the second end cap and a spring valve cooperating with said second end cap and said housing to control the flow of fluid through said openings, and for closing said openings in the second end cap remote from the end plate to fluid flow, whereby when the pressure within the housing increases and the pressure differential across the end cap exceeds a predetermined value, the said openings in the end cap remote from the end plate will be opened to permit fluid flow therethrough.
 8. An oil filter as in claim 7, wherein the anti-drain back valve is disposed between the first end cap and the end plate, said spring valve being constructed and arranged to engage the interior of the housing so as to load the filter media and the first end cap to help retain the anti-drain back valve in place.
 9. An oil filter as in claim 8, wherein the spring valve includes outwardly extending arms extending upwardly from the central portion of the spring valve.
 10. An oil filter as in claim 9, including depressions on the spring valve between the arms for permitting fluid flow between the spring valve and the interior of the housing and providing a fluid flow path should the spring valve be flattened against the interior of the housing in use.
 11. An oil filter as in claim 7, wherein the central portion of the second end cap is capable of being flexed from a first position against the spring valve to a second position away from the spring valve.
 12. An oil filter as in claim 11, wherein the spring valve has a central opening therein, the central portion of the second end cap closing the central opening when in the first position and opening the central opening when flexed to the second position, whereby, the spring valve is normally in the first position closing flow of oil and oil entering the housing through the inlet opening in the end plate passes through the filter media to be cleaned and when the filter media becomes clogged, the pressure within the housing increases and when the pressure exceeds a predetermined value, the central portion of the second end cap is flexed to the second position to permit oil to bypass the filter media and flow from the inlet opening in the end plate, through the central opening in the spring valve and the openings in the second end cap and out the outlet opening.
 13. An oil filter as in claim 12, including seal means between the second end cap an the spring valve to prevent oil from passing directly to the openings in the second end cap and bypassing the opening in the spring valve.
 14. An oil filter as in claim 11, wherein the spring valve is made from a plate and the second end cap has a substantially flat profile, the spring valve and the second end cap being constructed and arranged to operationally interengage and provide a relatively flat profile, with the overall height being little more than the height of the second end cap.
 15. An oil filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an anti-drain back valve for precluding return flow of oil through the inlet opening, an annular filter media disposed in said housing, said filter media having a first member at one end and an end cap at the other end, the first member having a plurality of openings spaced radially outwardly from the central axis thereof, the central portion of the first member being imperforate and substantially flat, and valve means cooperating with said first member and said housing for closing said openings in the first member to fluid flow, said valve means comprising a plate-like member having a flattened radial portion radially outward from an annular portion extending from a central portion thereof whereby when the pressure within the housing increases and the pressure differential across the first member exceeds a predetermined value, said openings in the first member will be opened to permit fluid flow therethrough, the valve means and the first member being constructed and arranged to operationally interengage and provide a relatively flat profile that is little more than the height of the first member.
 16. An oil filter as in claim 15, wherein the first member and the valve means are sealingly engaged to one another radially outwardly of the openings in the first member.
 17. An oil filter as in claim 16, wherein the valve means has an opening therein, and including seal means between the first member and the valve means to prevent oil from passing directly to the opening in the first member and bypassing the opening in the valve means.
 18. In a fluid filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an annular filter media disposed in said housing, said filter media having an end cap at each end, and a valve member for controlling flow of fluid through the inlet opening, the improvement comprising the end cap remote from the end plate having at least one opening in a central portion thereof and a spring cooperating with said end cap remote from the end plate and closing said opening in the central portion of the end cap remote from the end plate to fluid flow, the end cap remote from the end plate being responsive to the pressure within the housing for opening said opening in the central portion of the end cap remote from the end plate when the fluid differential pressure across the end cap remote from the end plate exceeds a predetermined value, the valve member comprising an anti-drain back valve disposed between the end cap adjacent the end plate and the end plate, said spring being constructed and arranged to engage the interior of the housing so as to load the filter media and the end cap adjacent to the end plate to help retain the anti-drain back valve in place, the spring having depressions thereon for providing a flow path should the spring be flattened against the interior of the housing in use.
 19. An oil filter comprising a housing that is open at one end, an end plate connected to said housing and closing said open end, said end plate having at least one inlet opening and an outlet opening therein, an anti-drain back valve for precluding return flow of oil through the inlet opening, an annular filter media disposed in said housing, said filter media having an end cap at each end, the end cap remote from the end plate having at least one opening spaced radially outwardly from the central axis thereof and a spring valve cooperating with said end cap remote from the end plate for closing said opening in the end cap remote from the end plate to fluid flow, whereby when the pressure within the housing increases and the pressure differential across the end cap remote from the end plate exceeds a predetermined value, said opening in the end cap remote from the end plate will be opened to permit fluid flow therethrough, the anti-drain back valve being disposed between the end cap adjacent the end plate and the end plate, said spring valve being constructed and arranged to engage the interior of the housing so as to load the filter media and the end cap adjacent to the end plate to help retain the anti-drain back valve in place and depressions formed on the spring valve for permitting fluid flow between the spring valve and the interior of the housing and providing a flow path should the spring valve be flattened against the interior of the housing in use. 